Crawler device for a crawler type vehicle

ABSTRACT

The present invention is a crawler device for a crawler type vehicle, which lowers the vehicle height, decreases the vehicle width, and exhibits superior stability during operation. For this purpose, in a crawler type vehicle having, on right and left sides of either one of front or rear portion, or both of the front and rear portions of a vehicle body ( 3 ), crawler devices each having a sprocket ( 12 ), an idler ( 16 A) disposed on a truck frame ( 15 ), and a crawler belt ( 11 ) passed around the sprocket ( 12 ) and the idler ( 16 A), the crawler device includes a front end link ( 181 ) coupled to a forward part of said truck frame ( 15 ) by means of a pin ( 181 D) at a lower end portion thereof and to the side of said vehicle body ( 3 ) by means of a pin ( 181 U) at the upper end portion thereof, and a rear end link ( 182 ) coupled to a rearward part of said truck frame ( 15 ) by means of a pin ( 182 D) at the lower end portion thereof and to said side of said vehicle body ( 3 ) at a position behind said front end link ( 181 ) by means of a pin ( 182 U) at the upper end portion thereof.

TECHNICAL FIELD

The present invention relates to a crawler device provided in a crawlertype of construction vehicle, a vehicle for traveling on an irregularground, or the like.

BACKGROUND ART

FIG. 45 is a side view of a construction vehicle 2 having a crawlerdevice in a triangular form. An upper revolving superstructure 4 ismounted on a vehicle body 3 of the vehicle 2, and a working machine 5,having a bucket or the like, is attached on the upper revolvingsuperstructure 4. The crawler devices 1 of triangular form, beingtraveling devices, are respectively provided at the front and the rear,and at the right and the left portions of the vehicle body 3.Specifically, a pair of right and left crawler devices 1A and 1A,coupled to a steering device and a driving steering device and a drivingdevice, are disposed at the front part of the vehicle body 3; and a pairof right and left crawler devices 1B and 1B, coupled to the drivingdevice, are disposed at the rear part of the vehicle body 3. In order tomake the explanation understandable, the crawler devices 1A are taken asa pair of right and left crawler devices coupled to the steering deviceand the driving device, and the crawler devices 1B are taken as a pairof right and left crawler devices coupled to the driving device.Further, the crawler devices 1A and/or the crawler devices 1B arecollectively called the crawler device 1.

The details of the crawler device 1 having a triangular form aredisclosed in, for example, Japanese Laid-open Patent No. 4-8682. Thiswill be explained with reference to FIG. 46. FIG. 46 is a sectional viewof the rear end crawler device 1B taken along the A—A line in FIG. 45.

A sprocket 12, rotationally driving a crawler belt 11, is fixedlyprovided on the external perimeter of the outside end portion of a wheelhub 31, which is on a side of the vehicle body 3 and is free to rotate.A bracket 13 is rotatably attached to the wheel hub 31 via a bearing 32.A truck frame 15, equipped with a roller 14, is fixedly provided at thelower portion of the bracket 13. The front end crawler device 1A has thesame configuration as above, and both of the crawler devices 1A and 1Bare free to swing about the respective sprocket 12. Each of the crawlerdevices 1 is supported on the vehicle body 3 by means of a suspensionmechanism (not illustrated). Specifically, in the vehicle 2, eachcrawler device 1 not only is in four-point contact with a road surface,but also can be evenly in contact with even an irregular ground surfacewith the aforesaid swing function of the crawler device 1.

The truck frame 15 of the aforesaid crawler device 1 in a triangularform has a recoil spring 17 at almost the center portion between a frontend idler 16A and a rear end idler 16B as shown in a schematic diagramin FIG. 47. When the front end idler 16A receives a large impactiveforce from the front, the recoil spring 17 contracts and the front endidler 16A moves to the position shown by an alternate long and two shortdashes line to thereby absorb the impactive force.

However, the aforesaid conventional crawler device 1 has the followingdisadvantages.

(1) The vehicle body 3 is supported by the truck frame 15 by means ofthe bearing 32, which is placed nearer to the side of the vehicle body 3than to the sprocket 12. However, the bearing 32 is fitted onto thewheel hub 31. Specifically, the bearing 32 is not provided on an axlebeam (not illustrated) and the vehicle body 3 itself, and dose notsupport the vehicle body 3. The wheel hub 31 is a rotary body fortransmitting a rotational force to the sprocket 12. Accordingly, unlessthe wheel hub 31 is constructed to have higher strength, there is adisadvantage in that the vehicle body 3 is difficult to be supportedwhile smoothly transmitting the rotational force to the sprocket 12. Itis extremely disadvantageous for a working vehicle with heavy weightlike the machines cited as an example. When the wheel hub 31 is highlystrengthened, the wheel hub 31 is inevitably increased in size.Specifically, there is a disadvantage in that the vehicle height isdifficult to be lowered.

(2) The wheel hub 31 is placed nearer to the vehicle body 3 than to thesprocket 12. Therefore in a large-sized vehicle which contains areduction gear such as a planetary gear train or the like, theconfiguration of the small space between the right and left sprockets 12and 12 is complicated. Accordingly, there are disadvantages in that thevehicle height is difficult to be lowered, in that the distance betweenthe sprockets 12 and 12 is difficult to be shortened (specifically, thevehicle width is difficult to be reduced), and in that themaintainability of the wheel hub 31 is worsened.

(3) The crawler device 1 is free to swing about the sprocket 12. Forthis reason, as shown in FIG. 48, there is a disadvantage in that thefront part of the front end crawler device 1A faces downwardly(specifically, stumbles) when the vehicle 2 collides with an obstacle 6in the front. The crawler device 1 is always free to swing; therefore,there is a disadvantage in that when an operation is carried out withthe working machine 5, the crawler device 1 swings, depending on thevariations in the load on the working machine 5, and on road conditions;and an operation to be carried out while standing firm cannot be carriedout. Specifically, there is a disadvantage of unsatisfactory stabilityduring operation.

SUMMARY OF THE INVENTION

The present invention is made to eliminate the aforesaid disadvantagesof the prior art, and its object is to provide a crawler device for acrawler type vehicle with a simple structure, which lowers the vehicleheight, decreases the vehicle width, has excellent maintainability, doesnot stumble even when colliding with an obstacle during traveling, andprovides superior operation stability in a working vehicle.

A first configuration of a crawler device for a crawler type vehicleaccording to the present invention is, in a crawler type vehicleincluding, on the right and the left sides of either one of a front or arear portion or both of the front and the rear portions of a vehiclebody, crawler devices, each having a sprocket being a driving wheel, anidler being a driven wheel disposed on a truck frame, and a crawler beltpassed around the sprocket and the idler, characterized by including afront end link, coupled to a forward part of the truck frame by means ofa pin at a lower end portion thereof and to the vehicle body side bymeans of a pin at the upper end portion thereof, and a rear end link,coupled to a rearward part of the truck frame by means of a pin at thelower end portion thereof and to the vehicle body side at a positionbehind the front end link by means of a pin at the upper end portionthereof.

According to the first configuration, when an external force in afore-and-aft direction is exerted on the truck frame, the truck framecan swing in the fore-and-aft directions, supported by the front linkand the rear link. Accordingly, when the idler collides with an obstacleduring traveling, the truck frame swings rearwardly and absorbs theimpact. For this reason, the conventional recoil spring becomesunnecessary, thereby simplifying the configuration.

A second configuration is, in the aforesaid first configuration,characterized by the sprocket being disposed on either one of the frontor the rear portion of the truck frame, and the idler being disposed onthe other one of the front or the rear portion of the truck frame.According to the second configuration, in addition to the operationaleffects in the first configuration, a so-called low drive configurationis established. Specifically, the vehicle height can be lowered, and theposition of the center of gravity is lowered, thereby improving thestability.

A third configuration is, in a crawler type vehicle including, on theright and left sides of either one of a front or a rear portion or bothof the front and the rear portions of a vehicle body, crawler deviceseach having a sprocket being a driving wheel, a front end idler and arear end idler being driven wheels respectively disposed at the frontand the rear positions of a truck frame disposed under the sprocket, anda crawler belt passed around the sprocket, the front end idler, and therear end idler, characterized by including:

a front end link, coupled to a forward part of the truck frame by meansof a pin at a lower end portion thereof and to the vehicle body side bymeans of a pin at the upper end portion thereof, and a rear end link,coupled to a rearward part of the truck frame by means of a pin at thelower end portion thereof and to the vehicle body side at a positionbehind the front end link by means of a pin at the upper end portionthereof.

In the aforesaid third configuration, the crawler device is specified tobe in a triangular form compared to the aforesaid first configuration.Consequently, according to the third configuration, the same operationaleffects as in the first configuration are obtained.

A fourth configuration is, in the aforesaid first or the thirdconfiguration, characterized by a quadric link structure, which isformed by the vehicle body, the truck frame, the front end link, and therear end link, having a side length on the truck frame side shorter thana side length on the vehicle body side. According to the fourthconfiguration, when the idler, or one of the front end idler and therear end idler collides with an obstacle while the vehicle is traveling,the truck frame swings in such a way that the front portion of the truckframe moves upwardly, and the rear portion of the truck frame movesdownwardly. Accordingly, the device can pass over the obstacle withoutstumbling thereon. Specifically, traveling performance on an irregularground is improved.

A fifth configuration is, in the aforesaid fourth configuration,characterized by a point of intersection of an axis of the front endlink and an axis of the rear end link being located inside the loop ofthe endless crawler belt. According to the fifth configuration, thepoint of intersection is located inside the loop of the crawler belt;therefore, the swing of the crawler device is increased.

A sixth configuration is, in the aforesaid first or third configuration,characterized by either one or both of the front end link and/or therear end link being of an extension type comprising of a turn buckletype, a grease cylinder type, or the like. According to the sixthconfiguration, the link is extended in a normal situation, and iscontracted at the time of attaching and detaching the crawler belt,thereby facilitating the operation of attaching and detaching thecrawler belt.

A seventh configuration is, in the aforesaid first or thirdconfiguration, characterized by upper rollers, which are allowed torotate in contact with the inner side surface of the upper part of theendless crawler belt, being respectively provided at two positions onthe vehicle body side corresponding to positions at the forward andrearward parts of the truck frame. Conventionally, when the crawlerdevice collides with an obstacle and the crawler device swings, thecrawler belt is slightly loosened. However, according to the seventhconfiguration, even if the crawler device swings, the upper rollers liftthe crawler belt from the inside thereof; therefore, the crawler belt isnot loosened. Specifically, the crawler belt is tightened. Accordingly,stability can be maintained during traveling.

An eighth configuration is, in the aforesaid first or thirdconfiguration, characterized by further including an arm which isprovided at the position on the vehicle body side corresponding to aposition which is above the crawler belt and on a vertical line passingthrough almost the center of a distance from the upper end portion ofthe front end link to the upper end portion of the rear end link, withthe center of the arm being free to swing in a vertical direction andthe length thereof being in a fore-and-aft direction, and rollersrespectively provided on the front end portion and the rear end portionof the arm, with the rollers being provided to be pressed against thecrawler belt downwardly from the upper surface of the crawler belt.According to the eighth configuration, even if the crawler deviceswings, either of two rollers presses the crawler belt downwardly fromthe outside; therefore, the crawler belt is not loosened. Specifically,the crawler belt is tightened. Consequently, stability can be maintainedduring traveling. Especially in the eighth configuration, the crawlerbelt is always pressed toward the sprocket side; therefore, skippingpitch and separation of the crawler belt on the sprocket is prevented,and the traveling performance is improved.

A ninth configuration is, in the aforesaid first or third configuration,characterized by either one of the front end link, coupling with thepins at the upper and the lower end portions of the front end link, orthe rear end link, coupling with the pins at the upper and the lower endportions of the rear end link, being an elastic member fixedly providedat either one or both of the vehicle body side and/or the truck frame.According to the ninth configuration, one side is supported by theelastic member while the other side is coupled by the link; therefore,even if the front end idler collides with an obstacle during traveling,the truck frame swings rearwardly, and the rear end idler movesdownwardly, thereby establishing the position to pass over the obstacle,and the traveling performance on an irregular ground is improved. Evenif the device collides with the obstacle, the elastic member absorbs theimpactive force.

A tenth configuration is, in a crawler type vehicle including, on rightand left sides of either one of a front or a rear portion or both of thefront and the rear portions of a vehicle body, crawler devices eachhaving: a sprocket, being a driving wheel, which is supported by meansof a bearing provided at the vehicle body side; a front end idler and arear end idler, being driven wheels respectively disposed at the frontand the rear positions of a truck frame disposed under the sprocket; anda crawler belt passed around the sprocket, the front end idler, and therear end idler; characterized by including an extendedly provided memberwhich is provided to extend from the vehicle body side over the sprocketto the outside thereof, with the bearing being provided at theextendedly provided member.

According to the tenth configuration, a wheel hub with a complicatedstructure or the like can be disposed on the outside of the vehicle, andthe sprocket can be supported at both ends. Accordingly, the small spacebetween the sprockets can be simplified. Specifically, the vehicleheight can be lowered, and the vehicle width can be decreased.Consequently, entry into a narrow path is facilitated and thetransportability is improved. If the wheel hub with a complicatedstructure is provided outside, maintainability is improved.

An eleventh configuration is, in the aforesaid tenth configuration,characterized by further including a front end link, coupled to aforward part of the truck frame by means of a pin at a lower end portionthereof and to the vehicle body side by means of a pin at the upper endportion thereof, and a rear end link, coupled to a position at arearward part of the truck frame by means of a pin at the lower endportion thereof and to the vehicle body side at a position behind thefront end link by means of a pin at the upper end portion thereof. Thefeature of the aforesaid eleventh configuration corresponds to thefeature of the aforesaid first configuration. Consequently, according tothe eleventh configuration, the same operational effects as provided bythe first configuration are obtained.

A twelfth configuration is, in the aforesaid second configuration,characterized by the truck frame having at least one roller at the lowerportion thereof between the idler and the sprocket, the crawler belthaving tread surfaces in a protrusion form at a predetermined pitchspaced with a predetermined gap, to be trod by the idler, the sprocket,and the roller; and a space between the idler and a roller adjacent tothe idler, a space between the sprocket and a roller adjacent to thesprocket, and a space between the idler and the sprocket beingrespectively expressed by

[(0.5±0.2)+N]×Lp

if N is set as zero or a natural number, and Lp is set as a crawler beltpitch.

Further, a thirteenth configuration is, in the aforesaid third or tenthconfiguration, characterized by the truck frame having at least oneroller at the lower portion thereof between the front end idler and therear end idler, the crawler belt having tread surfaces in a protrusionform at a predetermined pitch spaced with a predetermined gap to be trodby the front end idler, the rear end idler, and the roller; and a spacebetween the front end idler and a roller adjacent to the front endidler, a space between the rear end idler and a roller adjacent to therear end idler, and a space between the front end idler and the rear endidler being respectively expressed by

[(0.5±0.2)+N]×Lp

if N is set as zero or a natural number, and Lp is set as a crawler beltpitch.

According to the twelfth and the thirteenth configurations, even whenany one of the idlers (or the front side idler and the rear side idler),the sprocket, and the rollers are positioned on the predetermined gap ofthe crawler belt and is to fall in the predetermined gap, all of theothers ride on the tread surface. Accordingly, the occurrence of greaterpitching of the crawler device, based on the aforesaid predeterminedgap, can be prevented. Specifically, the vibration during traveling isdecreased; therefore, riding comfort is improved.

A fourteenth configuration is, in any one of the aforesaid first, third,and tenth configurations, characterized by either or both of a swingstopping mechanism, for stopping the swing of the truck frame at anyposition, and/or a swing control mechanism, for controlling the maximumswing of the truck frame, being provided between the vehicle body sideand the truck frame. According to the fourteenth configuration, theswing of the crawler device can be stopped at any position by using theswing stopping mechanism. If the swing control mechanism is used, theunlimited swing of the crawler device is eliminated. Specifically, ifthe vehicle body is, for example, a construction machine or the likeequipped with an excavator or the like, and when the operation iscarried out, the vehicle is stopped, and in this situation, the swingstopping mechanism is applied. Thus the crawler device maintains anangle of swing at the time of stopping the vehicle irrespective ofvariations in the load or the road conditions. Consequently, standingfirm operations can be carried out. Specifically, stability is securedin carrying out an operation.

A fifteenth configuration is, in any one of the aforesaid first, third,and tenth configurations, characterized by the endless crawler beltbeing made of rubber and having a plurality of raised portions atpredetermined pitches on the inner center portion thereof in a directionto be passed around, the sprocket having a plurality of engaging gearswith the raised portions on the outer perimeter and having cylindermembers, which are fixedly provided on the right and the left sides ofthe engaging gears and allow the outer perimeter surface thereof to abutthe surface surrounding the raised portions, and an external diameter ofthe sprocket being smaller than an external diameter of the top of theengaging gear.

According to the fifteenth configuration, when the raised portions ofthe crawler belt are meshed with the engaging gears of the sprocket, theengaging gears are engaged in the bottom surface and the side surface ofrespective raised portions by “(the external diameter of the top of theengaging gear−the external diameter of the sprocket)/2”. At the sametime, the external perimeter surfaces of the cylinder members forcefullycontact the surface surrounding the raised portions of the crawler belt.Accordingly, the crawler belt obtains a rotational driving force fromthe sprocket. Accordingly, a light weight crawler belt, without coremetals or the like, can be used for the crawler belt. Consequently, thesprocket can transmit a highly efficient rotational force to the crawlerbelt. Specifically, higher tractive force can be obtained; the crawlerbelt is difficult to fall off by the engaging amount δ; skids aredifficult to occur; and the size, the noise, and the cost can bereduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of a crawler device in a triangularform in a first embodiment according to the present invention;

FIG. 2 is a sectional view taken along the B—B line in FIG. 1;

FIG. 3 is an explanatory view of the operation of the crawler device ofFIG. 1;

FIG. 4 is a side elevational view of a vehicle equipped with crawlerdevices of FIG. 1;

FIG. 5 is a side elevational view of a crawler device in a triangularform in a second embodiment according to the present invention;

FIG. 6 is a sectional view taken along the C—C line in FIG. 5;

FIG. 7 is an explanatory view of the operation of the crawler device ofFIG. 5;

FIG. 8 is a side elevational view of a low drive type of crawler devicein a third embodiment according to the present invention;

FIG. 9 is an explanatory view of the operation of the crawler device inFIG. 8;

FIG. 10 is a side view of a vehicle equipped with the crawler device inFIG. 8;

FIG. 11 is a fragmentary sectional view of a turn buckle type of linkaccording to another embodiment of the present invention;

FIG. 12 is a fragmentary sectional view of a grease cylinder type oflink according to another embodiment of the present invention;

FIG. 13 is a side elevational view of a crawler device showing a firstexample of a crawler belt tightening mechanism according to anotherembodiment of the present invention;

FIG. 14 is a sectional view taken along the D—D line in FIG. 13;

FIG. 15 is an explanatory view of the operation of the crawler device inFIG. 13;

FIG. 16 is a side elevational view of a crawler device showing a secondexample of a crawler belt tightening mechanism according to anotherembodiment of the present invention;

FIG. 17 is an explanatory view of the operation of the crawler device inFIG. 16;

FIG. 18 is a side elevational view of a crawler device showing a thirdexample of a crawler belt tightening mechanism according to the presentinvention;

FIG. 19 is a sectional view taken along the E—E line in FIG. 18;

FIG. 20 is a sectional view taken along the F—F line in FIG. 18;

FIG. 21 is an explanatory view of the operation of the crawler device inFIG. 18;

FIG. 22 is a side elevational view of a crawler device showing a shockabsorbing device according to another embodiment of the presentinvention;

FIG. 23 is an explanatory view of the operation of the crawler device inFIG. 22;

FIG. 24 is a side elevational view of the crawler device showing a mudscraper mechanism according to another embodiment of the presentinvention;

FIG. 25A is a sectional view taken along the G—G line in FIG. 24;

FIG. 25B is a view seen in a direction of the arrow H in FIG. 24;

FIG. 26A is a sectional view taken along the J—J line in FIG. 24;

FIG. 26B is a sectional view taken along the K—K line in FIG. 24;

FIG. 27 is a side elevational view of an essential part of a crawlerdevice showing a second example of a swing control mechanism accordingto another embodiment of the present invention;

FIG. 28 is a sectional view taken along the M—M line in FIG. 27;

FIGS. 29A, 29B, and 29C are explanatory views of the operation of theswing control mechanism in FIG. 27, and FIG. 29A is an explanatory viewof the situation where the stoppers are separated;

FIG. 29B is an explanatory view of the situation wherein the stoppersstart to be in contact with each other;

FIG. 29C is an explanatory view of the situation in that the stoppershas completed the contact;

FIG. 30 is a side elevational view of the crawler device in a triangularform according to another embodiment of the present invention;

FIG. 31 is a sectional view taken along Q—Q line in FIG. 30;

FIG. 32 is an explanatory diagram of a power train of the crawler devicein FIG. 30;

FIG. 33 is an explanatory diagram when the conventional power train isapplied to the crawler device in FIG. 30;

FIG. 34 is an explanatory diagram of another example of the power trainin FIG. 32;

FIG. 35 is an explanatory diagram of another example of the power trainin FIG. 32;

FIG. 36 is a plan view of a crawler belt according to the embodiments ofthe present invention;

FIG. 37 is a sectional view taken along the R—R line in FIG. 36;

FIG. 38 is a side elevational view of the crawler belt in FIG. 36;

FIG. 39 is a schematic explanatory view of the placement of a sprocket,idlers, and two rollers according to the embodiments of the presentinvention;

FIG. 40 is a schematic explanatory view when a number of rollers areused in FIG. 39;

FIG. 41 is a perspective view of the crawler belt passed around thesprocket according to the embodiments of the present invention;

FIG. 42 is a sectional view of an engaging portion of the crawler beltand the sprocket in FIG. 41;

FIG. 43 is a side elevational view of an engaging portion of the crawlerbelt and the sprocket in FIG. 41;

FIG. 44 is an explanatory view of a roller rolling on the crawler beltin FIG. 41;

FIG. 45 is a side elevational view of a working vehicle equipped with aconventional crawler device in a triangular form;

FIG. 46 is a sectional view taken along the A—A line in FIG. 45;

FIG. 47 is a schematic side elevational view of the crawler device inFIG. 45; and

FIG. 48 is a view of the operation of the working vehicle in FIG. 45.

BEST MODE FOR CARRYING OUT THE INVENTION

A first embodiment will be explained with reference to FIGS. 1-4. Thefirst embodiment is a crawler device 1 in a triangular form as shown inFIG. 1. A sprocket 12 is attached to a vehicle body 3. The vehicle body3 is coupled to a front portion of a truck frame 15 via a front end link181 by means of coupling pins 181U and 181D, and the vehicle body 3 iscoupled to a rear portion of the truck frame 15 via a rear end link 182by means of coupling pins 182U and 182D. Specifically, the vehicle body3, the truck frame 15, the front end link 181, and the rear end link 182constitute a quadric link. A distance L2 between the coupling pins 181Dand 182D is designed to be shorter than a distance L1 between thecoupling pins 181U and 182U (L2<L1). An idler 16A is attached to thefront end of the truck frame 15, an idler 16B is attached to the rearend of the truck frame 15, and two rollers 14A and 14B are attached tothe lower surface of the truck frame 15.

A crawler belt 11 is passed around the sprocket 12, the front end idler16A, the rear end idler 16B, the front end roller 14A, and the rear endroller 14B. As FIG. 2 illustrates, a steering knuckle arm 33 isconnected to the coupling pin 182U.

The steering knuckle arm 33 is supported (not illustrated) by thevehicle body 3, and is provided with a steering tie rod 331 so as toextend therefrom. The sprocket 12 is freely rotated, receiving a drivingforce from the side of the vehicle body 3, which is transmitted from apropeller shaft (not illustrated) and a universal joint (notillustrated), which are contained in an axle beam 34 (see FIG. 6), inthat order. Specifically, the first embodiment is a front end crawlerdevice 1A which is coupled to a steering device and a driving device.The operational effects of the aforesaid first embodiment are asfollows.

As FIG. 3 illustrates, when a force is exerted on the front end idler16A from the front as shown by an arrow F, in the truck frame 15, thefront end idler 16A moves to the rear and upwardly as shown by a brokenline arrow a, while the rear end idler 16B moves to the rear anddownwardly as shown by a broken line arrow b according to the aforesaidrelationship “L2<L1” of the quadric link. Accordingly, as shown in FIG.4, the front end crawler device 1A is in a position to pass over anobstacle 6 in front, and does not stumble as in the prior art. When thecrawler device 1 collides against the obstacle 6, the impactive force isabsorbed by the rearward movement of the truck frame 15 based on thedeformation of the quadric link. This eliminates the need for the recoilspring 17 of the prior art. Specifically, the configuration issimplified. The vehicle body 3 is supported by means of the knuckle arm33 with a simple structure, thereby eliminating the need for the bearing32 of the prior art. Specifically, a rotational force is transmitted tothe sprocket 12 without laboring, and the configuration between thesprockets 12 and 12 can be simplified; therefore, the vehicle height islowered, the vehicle width is decreased, and the maintainability isimproved.

In the first embodiment, the front end crawler device 1A is supported bya front end link 181 and a rear end link 182, but it is suitable thatonly the rear end crawler device 1B is supported by a front end link 181and a rear end link 182, or it is suitable that both of the crawlerdevices 1A and 1B are supported by a respective front end link 181 and arespective rear end link 182.

A second embodiment is explained with reference to FIGS. 5-7. The secondembodiment is also the crawler device 1 in a triangular form. It shouldbe noted that the same components as in the first embodiment are giventhe identical symbols and numerals to omit the explanation thereof, andonly the parts different from the first embodiment will be explained(ditto for the other embodiments of which details will be explainedbelow).

In FIGS. 5 and 6, the front end of a bracket 35, which is fixedlyprovided at the vehicle body 3 (see FIG. 4), is coupled to the forwardpart of the truck frame 15 via the front end link 181 by means of thecoupling pins 181U and 181D, and the rear end of the bracket 35 iscoupled to the rearward part of the truck frame 15 via the rear end link182 by means of the coupling pins 182U and 182D. The distance L2 (seeFIG. 1) between the coupling pins 181D and 182D is shorter than thedistance L1 (see FIG. 1) between the coupling pins 181U and 182U(L2<L1), and a point of intersection of the axis of the front end link181 and the axis of the rear end link 182 (specifically, a point ofintersection P of an extension of the line connecting the coupling pins181U and 181D and an extension of the line connecting the coupling pins182U and 182D) is located inside the loop of the endless crawler belt11. Stoppers 351 and 351 are fixedly provided at the front end and therear end of the bracket 35, and stoppers 151 and 151 are provided at thefront end and the rear end of the truck frame 15 so as to be abutted tothe aforesaid stoppers 351 and 351 when the crawler device 1 swingsgreatly. The bracket 35 is fixedly provided at the axle beam 34 which isin the side of the vehicle body 3 as shown in FIG. 6. Specifically, thesecond embodiment is the rear end crawler device 1B coupled to thedriving device. The aforesaid second embodiment has the followingoperational effects.

As shown in FIG. 7, when the front end idler 16A collides with a bump onan uneven ground with large bumps and potholes, a gutter, or the likeduring traveling, and when the force F is exerted from the front, thetruck frame 15 is moved toward the rear. At this time, an angle of swingof the crawler device 1 becomes larger according to the relationship ofthe aforesaid “L2<L1”, and the relationship of the location of the pointof intersection P, and the amount of the rising h of the front end idler116A relative to the rear end idler 16B becomes larger. Accordingly, thecrawler device 1 (specifically, the vehicle 2) can pass over a largebump. It should be noted that in this configuration, a great angle ofswing is obtained; therefore, the stoppers 351 and 151 at either thefront or the rear abut each other to control the swing within a properangle. Specifically, the stoppers 351 and 151 constitute a swing controlmechanism.

A third mechanism will be explained with reference to FIGS. 8-10. Thethird embodiment is a low drive type of crawler device 1. As shown inFIG. 8, the front end idler 16A is attached on the front end portion ofthe truck frame 15, and the sprocket 12, driven by a hydraulic motor(not illustrated), is attached at the rear end portion thereof. Theidler 16A only means the front end idler 16A in the third embodiment.The front end of the bracket 35, which is fixedly provided at thevehicle body 3 (refer to FIG. 4), and the front portion of the truckframe 15 are coupled via the front end link 181 by means of the couplingpins 181U and 181D, and the rear end of the bracket 35 and the rearportion of the truck frame 15 are coupled via the rear end link 182 bymeans of the coupling pins 182U and 182D. A roller 36 is provided at theupper portion of the bracket 35. The crawler belt 11 is passed aroundthe front end idler 16A, the sprocket 12, the front end roller 14A, therear end roller 14B, and the upper end roller 36. The third embodimentalso has the relationship “L2<L1” and the relationship that the point ofintersection P is located inside the loop of the crawler belt 11, as inthe second embodiment. Further, the stoppers 351 and 351 at the frontand the rear ends of the bracket 35 and the stoppers 151 and 151 at thefront and 31 the rear portions of the truck frame 15 constitute a swingcontrol mechanism. The aforesaid third embodiment has the followingoperational effects.

As shown in FIG. 9, when the front end idler 16A collides with a bump onan uneven ground with large bumps and potholes, a gutter, or the likeduring traveling, the crawler device 1 swings as in the secondembodiment (to be precise, the front end idler 16A ascends while thesprocket 12 descends), and the crawler device 1 can easily pass overeven a large bump. If the angle of swing becomes greater, the stoppers351 and 151 control the swing. In addition, the sprocket 12 is providedat the rear portion of the truck frame 15; therefore a height S of thecrawler device 1 can be lowered as is shown in FIG. 10 to provide aso-called low drive type. Consequently, a height H of the vehicle 2 canbe lowered by the lowered height of the crawler device 1; thereforestability is improved when traveling on an irregular ground. Inaddition, the angle at which the crawler belt 11 is passed around thesprocket 12 is increased; thereby reducing skipping pitch and separationof the crawler belt by the increased angle.

In the first, the second, and the third embodiments, the front end link181 and the rear end link 182 have a fixed length, but they can be anexpansion type as follows.

For example, as shown in FIG. 11, they can be a turnbuckle type.Specifically, a right hand screw hole a3 is provided at one end of afirst joint a2, which has a coupling pin hole al at the other endthereof. Meanwhile, a left hand screw hole a6 is provided at one end ofa second joint a5, which has a coupling pin hole a4 at the other endthereof. A screw a9, which has a right hand screw a7 at one end and hasa left hand screw a5 at the other end, is screwed into the right handscrew hole a3 and the left hand screw hole a6. When the screw a9 isturned, the length of the front end link 181 or the rear end link 182 isreduced, and the crawler belt 11 is loosened. On the other hand, whenthe screw a9 is turned in the reverse direction, the front end link 181or the rear end link 182 is extended, and the crawler belt 11 istightened. Specifically, the attachment and detachment and the tensionadjustment of the crawler belt 11 can be facilitated.

Further, for example, as is shown in FIG. 12, the links can be a greasecylinder type. Specifically, this type is composed of a first member b3having the coupling pin hole a1 at one end, an external cylinder b1opened toward the other end, and a grease cylinder b2 which is providedinside the external cylinder b1 and is opened toward the other end, anda second member b6 having a coupling pin hole a4 at one end, an externalcylinder b4 fitted into the external cylinder b1 at the other end, and apiston b5 which is fitted into the external cylinder b4 and is insertedinto the grease cylinder b2. A grease nipple b8 is provided at one endof the first member b3, and grease b7 is injected into the cylinder b2from this grease nipple b8. The grease nipple b8 has a valve (notillustrated).

When the valve is opened and the grease b7 in the grease cylinder b2 isdischarged outside from the grease nipple b8, the length of the frontend link 181 or the rear end link 182 is reduced, and the crawler belt11 is loosened. On the other hand, when the valve is closed and thecrease b7 is supplied into the grease cylinder b2 from the grease nippleb8, the front end link 181 or the rear end link 182 is extended, and thecrawler belt 11 is tightened. Specifically, the attachment anddetachment and the tension adjustment of the crawler belt 11 can befacilitated. In this type, a load in the axial direction is received bythe crease 7, and a load in a bending direction is received by theexternal cylinders b1 and b4.

As for preferable mechanism for the first, the second, and the thirdembodiments, which only tightens the crawler belt, for example, thefollowing various configurations can be shown as examples.

(1) FIGS. 13-15 show a first example of a crawler belt tighteningmechanism. As shown in FIGS. 13 and 14, the front end link 181 and therear end link 182 are provided at the outer perimeters of the couplingpins 181U and 182U, and the upper rollers 83A and 83B are attached atthe outer perimeters of the respective bosses 81 and 81 by the bearings82 and 82 so as to be free to rotate. The upper rollers 83A and 83Bsupport the lower surface of the upper portion of the crawler belt 11with the sprocket 12 between them. In the third embodiment, the rollers83A and 83B support the lower surface of the upper portion of thecrawler belt 11 with the upper roller 36 between them instead of thesprocket 12.

Specifically, during traveling, as shown in FIG. 15, when the front endidler 16A collides with a bump or the like, and the truck frame 15swings, the crawler belt 11 tends to be slightly loosened, but the rearend upper roller 83B lifts the crawler belt 11 and gives tension to thecrawler belt 11. Accordingly, the crawler belt 11 does not loosen.Specifically, skipping pitch or the like caused by a loosened belt canbe prevented on the sprocket 12.

(2) FIGS. 16 and 17 show a second example of the crawler belt tighteningmechanism. In the first example, the front and rear upper rollers 83Aand 83B are provided at the coupling pins 181U and 182U, but in thesecond example, as shown in FIG. 16, they are provided at the side ofthe vehicle body 3 corresponding to the positions which are at bothsides of the sprocket 12 and away from the coupling pins 181U and 182U.In the second example, as shown in FIG. 17, as in the first example,when the front end idler 16A collides with a bump or the like, and thetruck frame 15 swings, the crawler belt 11 ends to be slightly loosened,but the rear end upper roller 83B lifts the crawler belt 11 and givestension to the crawler belt 11. Accordingly, the crawler belt 11 is notloosened. Specifically, skipping pitch or the like caused by a loosenedcrawler belt on the sprocket 12 can be prevented.

(3) FIGS. 18-21 are a third example of the crawler belt tighteningmechanism. As shown in FIGS. 18 and 19, a bracket 101 is fixedlyprovided at the side of the vehicle body 3 at the top of the sprocket12. The pivot pin 104 on the bracket 101 supports a center portion of anarm 103, which has rollers 102A and 102B rotatably attached at bothends, so as to freely swing. The rollers 102A and 102B press, in adirection of the sprocket 12, the upper surface of the portion of thecrawler belt 11 which is passed around the upper portion of the sprocket12 in a direction of the sprocket 12. FIG. 20 is a sectional view of theroller 102B portion, and the roller 102B is rotatably attached by meansof bearings 106 to a shaft 105, which is fixedly provided at the frontend of the arm 103.

Specifically, during traveling, as shown in FIG. 21, when the front endidler 16A collides with a bump or the like and the truck frame 15swings, the triangular form of the crawler belt 11 is deformed and aslight looseness tends to occur. At this time, following the deformationof the crawler belt 11, the arm 103 swings about the shaft 104. Here,the rollers 102A and 102B always abut the upper surface of the crawlerbelt 11, and press the crawler belt 11 in the direction of the sprocket12. Therefore, the crawler belt 11 is not loosened. Specifically,skipping pitch or the like caused by a loosened crawler belt on thesprocket 12 can be prevented.

Next, representative examples of a shock absorbing device, preferablefor the first, the second, and the third embodiments, are described withreference to FIGS. 22 and 23. As shown in FIG. 22, an elastic member 37,such as rubber, is attached between a bearing surface 352 of the bracket35 (see FIG. 5 in the second embodiment or FIG. 8 in the thirdembodiment. Corresponding to the vehicle body 3 in FIG. 1 in the firstembodiment.) in front of the sprocket 12 and a bearing surface 152,provided on the upper surface of the front portion of the truck frame15. The rear end link 182 is coupled to a portion of the bracket 35 atthe rear of the sprocket 12 by means of the coupling pin 182U, and theother end of the rear end link 182 is coupled to the rear portion of thetruck frame 15 by means of the coupling pin 182D. The relationshipbetween a horizontal distance L4 from a vertical line, passing throughthe center of the sprocket 12 up to the center of the coupling pin 182Uand a horizontal distance L3, from the aforesaid vertical line up to thecenter of the coupling pin 182D, is “L3<L4”.

Specifically, during traveling, when the external force F is exerted onthe front end idler 16A from the front, or when the front end idler 16Aruns on to the obstacle 6 on the ground as shown in FIG. 23, the elasticmember 37 is compressed and deformed to absorb the shock. Accordingly,the shock is decreased, and riding comfort is increased. Further, thefront end idler 16A is ascended while the rear end idler 16B isdescended; therefore, the crawler device can easily move over a bumpsuch as the obstacle 6.

Next, representative examples of a mud scraping mechanism, preferablefor the first, the second, and the third embodiments, will be describedwith reference to FIGS. 24, 25A, 25B, 26A, and 26B. In FIG. 24, firstscrapers 3S3 and 353 are provided at the upper end portions of thebracket 35, which is fixedly provided at the vehicle body 3 (see FIG.4), at positions in front of and at the rear of the sprocket 12. Theends thereof are positioned to the inner surface of the crawler belt 11,and as shown in FIGS. 25A and 25B, notches 3531 and 3531, for escaping araised portion 111 of the crawler belt 11, are provided. The width ofeach of the first scrapers 353 and 353 almost equals the width of thecrawler belt 11. In this example, as shown in FIG. 24, second scrapers153 and 153 are provided at the front and rear portions of the truckframe 15. The upper ends of the second scrapers 153 and 153 are alsoclose to the inner surface of the crawler belt 11, and as shown in FIG.26A, end second scraper 153 is fixedly provided at the respectivestopper 151 of the truck frame 15, and the width thereof almost equalsthe width of the crawler belt 11. Further, as shown in FIG. 26B, thenotches 1531 and 1531, for escaping the raised portions 111 which areprovided at the crawler belt 11, are provided in the upper end of thesecond scraper 153.

Specifically, both of the first scrapers 353 and the second scrapers 153scrape earth and sand which are accumulating on the inner surface of thecrawler belt 11 when the crawler belt 11 is rotated. Accordingly, earthand sand is prevented from being caught in the portion between thecrawler belt 11 and the sprocket 12. Thereby skipping pitch of thecrawler belt 11 on the sprocket 12 is prevented. Further, abrasion,breakage of a seal or the like, hydraulic leakage, and the like, areprevented.

Next, a second example of a swing control mechanism will be explained.As shown in FIGS. 27 and 28, a pair of stoppers 351 a and 351 a arefixedly attached forward of the bracket 35, which is fixedly provided atthe vehicle body 3 (see FIG. 4), in parallel relative to the widthdirection of the vehicle body 3. Meanwhile, a pair of stoppers 151 a and151 a are rotatably attached at the upper surface of the front end ofthe truck frame 15 in parallel to each other by means of pins 154 and154. When the truck frame 15 swings with the front part going up, bothof the stoppers 351 a and 151 a are abutted to each other. An abutsurface 351 b of the stopper 351 a is angled at an angle α relative to avertical line. The pin 154 is located at a position higher than theposition of the center of gravity of the stopper 151 a by apredetermined distance, and an abut surface 151 b for the abut surface351 b of the stopper 351 a is angled at an angle β relative to avertical line. Accordingly, the stopper 151 a always keeps the angle βrelative to the vertical line irrespective of the swing of the truckframe 15. Further, “α>β”. It should be noted that a similar stopperdevice is also provided in the rear of the bracket 35 and the truckframe 15.

Specifically, according to the aforesaid second example of a swingcontrol mechanism, the following operational effects are obtained. In anormal situation, as shown in FIG. 29A, both of the stoppers 351 a and151 a are spaced from each other. When the truck frame 15 swings and theangle of swing reaches a predetermined value, as shown in FIG. 29B, theabut surface 351 b of the stopper 351 a and the abut surface 151 b ofthe stopper 151 a start to abut each other. In this situation, asdescribed above, the abut surface 351 b of the stopper 351 a is angledat the angle α relative to a vertical line, while the abut surface 151 bof the stopper 151 a is angled at the angle β relative to a verticalline, and “α>β”. Therefore the abut surface 351 b of the stopper 351 aabuts the upper end portion of the abut surface 151 b of the stopper 151a at first. When the truck frame 15 swings further, as shown in FIG.29C, the stopper 151 a rotates around the pin 154, and the abut surface351 b of the stopper 351 a abuts the entire surface of the abut surface151 b of the stopper 151 a. Thereby earth and sand stuck to the abutsurface is removed downwardly, and the accumulation of earth and sand oneither of the abut surfaces 351 b and 151 b is eliminated. Accordingly,a decrease in the angle of swing of the truck frame 15, caused by theaccumulation of earth and sand on the abut surfaces 351 b and 151 b, isprevented; and excellent traveling is secured.

Next, examples of a mechanism, preferable for supporting a workingvehicle of a heavy weight, will be described with reference to FIGS.30-32, 34, and 35. In FIGS. 30 and 31, a wheel hub 31 is rotatablyprovided at an axle beam 34. The wheel hub 31 has the sprocket 12 on theouter perimeter thereof, and the crawler belt 11 is passed around theouter perimeter of the sprocket 12. The axle beam 34 is provided so asto go around the outside of the wheel hub 31 and the sprocket 12 toextend outwardly, and has an extendedly provided member 341. Theextendedly provided member 341 is coupled to the front end link 181 bymeans of the coupling pin 181U, and is coupled to the rear end link 182by means of the coupling pin 182U. The stoppers 351 and 351 are providedat the front and the rear portions of the extendedly provided member341, and the stoppers 151 and 151 are provided at the front and the rearportions of the truck frame 15 so as to abut the aforesaid stoppers 351and 351.

The inner configurations of the axle beam 34 and the wheel hub 31 willbe explained with reference to FIG. 32. In order to make the explanationeasier, FIG. 32 is a power train diagram (FIGS. 33-35 described beloware also power train diagrams). As shown in FIG. 32, the axle beam 34includes a differential 343, which is rotationally driven by a driveshaft 342 led from a transmission (not illustrated), and propellershafts 344 and 344 extend from the differential 343 in the right andleft directions of the vehicle body 3. The outer ends of both of thepropeller shafts 344 are sun gears 311 of planetary gear trainscontained in the wheel hubs 31. A ring gear 312 of the planetary geartrain is fixed at the axle beam 34 and is not able to rotate. Aplanetary gear 313 of the planetary gear train is meshed with the sungear 311 and the ring gear 312. A planetary carrier of the planetarygear train, which supports the planetary gear 313, is the aforesaidwheel hub 31. Accordingly, the rotational force of the propeller shaft343 is decreased at the planetary gear train, and rotationally drivesthe sprocket 12 through the wheel hub 31 to rotate the crawler belt 11.Here, an external outer end portion 341 a has a bearing 32 a, andsupports the wheel hub 31 from the outside. The wheel hub 31 is alsosupported by a bearing 32 b fitted onto the axle beam 34 from the sideof the vehicle body 3. It should be noted that a reduction gearcontained in the wheel hub 31 is not necessarily a planetary gear train,and an ordinary reduction gear, simply combining a plurality of gears,can be suitable.

The operational effects of the aforesaid examples of the configurationwill be explained, comparing with the prior art in FIG. 33. It should benoted that in order to facilitate the comparison, FIG. 33 includes theconfiguration in FIG. 46, which is the prior art, and is composed inaccordance with the aforesaid example of the configuration in FIG. 32.

As shown in FIG. 33, in the prior art, as described above, first of all,the vehicle body 3 is supported on the truck frame 15 with the bearing32, which is located nearer to the side of the vehicle body 3 than tothe sprocket 12. Accordingly, unless the wheel hub 31 is highlystrengthened, it is difficult to support the vehicle body 3 whilesmoothly transmitting a rotational force to the sprocket 12. This isextremely disadvantageous for the working vehicle 2 of a heavy weight asthe vehicle cited as an example. If the wheel hub 31 is to be highlystrengthened, the wheel hub 31 inevitably has a larger size.Accordingly, it is difficult to reduce the vehicle height. Second, thewheel hub 31 is located nearer to the vehicle body 3 than to thesprocket 12. Therefore in the vehicle 2 of a large size in which thewheel hub 31 contains the reduction gear such as the planetary geartrain or the like, the configuration in the small space between thesprockets 12 and 12 is complicated. Consequently, the vehicle height isdifficult to be reduced, the distance between the sprockets 12 and 12 isdifficult to be reduced (specifically, the vehicle width is difficult tobe reduced), and the maintainability of the wheel hub 31 is worsened.

However, in the aforesaid example of the mechanism of the invention, thewheel hub 31 is supported with the bearings 32 a and 32 b. In thisexample, both sides are supported, therefore the inner bearing 32 b ismade smaller, and the outer bearing 32 a is made larger. Accordingly,the planetary gear train is located at an outer position compared to thesprocket 12, and is contained in the wheel hub 31. Specifically, theconfiguration of the portion between the sprockets 12 and 12 issimplified, the vehicle height can be reduced, the distance between thesprockets 12 and 12 can be shortened, the vehicle width can be madesmaller, and the maintainability of the wheel hub 31 can be improved.

The effect will be more understandable if it is seen in a horizontalshaft type of vehicle 2, which is used as a bulldozer or the like, shownin FIG. 34. Specifically, the vehicle 2 has a bevel and pinion 343 bhaving right and left clutch and brake 343 a for transmitting or cuttingoff high torque instead of the aforesaid differential 343. In this case,in order to transmit or cut off high torque, the clutch and brake 343 aand the planetary gear train in the wheel hub 31 have a larger size.However, if it is constructed in such a way as to support the wheel hub31 with the bearings 32 a and 32 a as shown in FIG. 34, sufficient spaceis secured for the clutch and brake 343 a and for the bevel and pinion343 b requiring space for transmitting or cutting off high torque.Specifically, the configuration of the portion between the sprockets 12and 12 becomes simple, the vehicle height is lowered, the vehicle widthis reduced, and the maintainability of the wheel hub 31 is improved.

As shown in FIGS. 31 and 32, the aforesaid example of the mechanism hastwo brake mechanisms. A first brake mechanism 71 is composed of a brakedisc 71 a, provided at the outer perimeter of the wheel hub 31, a brakepad portion 71 b, which is fixedly provided at the axle beam 34 andcatches the aforesaid brake disc 71 a therein, and a hydraulic orpneumatic cylinder (not illustrated) which operates the brake padportion 71 b and makes it catch the brake disc 71 a therein. A secondbrake mechanism 72 is composed of a brake disc 72 a, provided at theouter surface of the truck frame 15, a brake pad portion 72 b, which isfixedly provided at the axle beam 34 and catches the brake disc 72 atherein, and a hydraulic or pneumatic cylinder (not illustrated) whichmakes the brake pad portion 72 b catch the brake disc 344 therein.

The operational effects of the first and second brake mechanisms 71 and72 will be explained. While the vehicle 2 is traveling, both of thebrake mechanisms 71 and 72 are released. Accordingly, the vehicle 2 cansmoothly travel without stumbling. Braking is performed by applying thefirst brake mechanism 71 during traveling. Meanwhile, when an operationis carried out by using the working machine 5 as in the example, thevehicle 2 is stopped, and in this situation, both of the brakemechanisms 71 and 72 are applied, or the second brake mechanism 72 isapplied. Thereby, the crawler device 1 maintains an angle of swing whenthe vehicle stopping irrespective of any variations in load and the roadconditions. Thus a standing firm operation can be carried out.Specifically, stability in working can be secured. In other words, thesecond brake mechanism 72 serves as the aforesaid swing stoppingmechanism. Though the first and the second braking devices 71 and 72 areof a brake pad type, they can be a band type, disc and clutch type, orthe like. It should be noted that a brake pad type can be constructed tobe more compact than a band type, a disc and clutch type, or the like.

The aforesaid example of the mechanism is used for the rear end crawlerdevice 1B, coupled to the driving device as shown in FIGS. 31, 32, and34, but as shown in FIG. 35, the pin coupling 331 of the knuckle arm 33to the vehicle body 3 can be performed; then the knuckle arm 33 and theextendedly provided member 341 can be integrated, and a tie rod 331 canbe connected to the knuckle arm 33. Specifically, the crawler device 1can be steered by moving the tie rod 331 in right and left directions inFIG. 35. In this situation, as for the sprocket 12, the propeller shaft341 contained in the axle beam 34 rotationally drives the sun gear 311by way of a universal joint 345. Specifically, the aforesaid example ofthe mechanism can be used for the front end crawler device 1A coupled tothe steering device and the driving device.

In the first and second embodiments, the front end idler 16A, the rearend idler 16B, and the rollers 14A and 14B are placed with therelationship {[(0.5±0.2)+N]Lp} being respectively established for afirst space Lpa between the front end idler 16A and the roller 14Aclosest thereto, a final space LPb between the final roller 14B and therear end idler 16B, and the entire space LPn between the front end idler16A and the end side entire space LPn between the front side idler 16Aand the rear side idler 16B. Here, N is zero or a natural number, and Lpis a crawler pitch (hereinafter referred to as a predetermined pitchLp). According to the above, an effect, which reduces the swing andvertical vibrations of the vehicle 2, is obtained. The details will beexplained below with reference to FIG. 36 to FIG. 40.

The crawler belt 11 is made of rubber, and is composed of a rubber belt111, core metals 112, and core wires 113 as shown in FIG. 37. The coremetals 112 are laid in the rubber belt 111 transverse to a longitudinaldirection of the belt 111 at equal intervals in order. Each core metal112 is provided with tread surfaces 112 a and 112 b in a protrusionform, which face each other at the center portion in a width directionof the rubber belt 111 with a space between them, and which are coupledwith a pin portion 112 c. A pair of blade portions 112 d and 112 c areintegrally formed outside the tread surfaces 112 a and 112 b in a widthdirection thereof The tread surfaces 112 a and 112 b are protruded tothe inner circumferential surface side of the rubber belt 111 so as tobe rolling surfaces of the front end idler 16A, the rear end roller 16B,the roller 14A, and the roller 14B. A length La of the tread surface 112a has the same length as a length Lb of the tread surface 112 b. At thecenter portion in a circumferential direction of the rubber belt 111, ahole 114 is provided between the pin portions 112 c adjacent to eachother. The tread surfaces 112 a, and the tread surfaces 112 b arerespectively spaced with a gap δ1 between them in a longitudinaldirection of the rubber belt 111 as shown in FIG. 38. A plurality ofcore wires 113 are laid inside the rubber belt 111 at the outerperimeter side of the core metals 112 as reinforcements of the rubberbelt 111.

Specifically, while the vehicle 2 is traveling, the rollers 14A and 14B,and the front and rear idlers 16A and 16B are rolling on the treadsurfaces 112 a and 112 b. At this time, as shown, for example, in FIG.38, the roller 14A slips downwardly when it is positioned at the gap δ1.Thus, the truck frame 15 swings unnecessarily, and vibrates verticallyto be a source of vibrations during traveling.

However, when the front and the rear idlers 16A and 16B, and the rollers14A and 14B are laced as described above, even if any one of the frontand the rear idlers 16A and 16B, and the rollers 14A and 14B ispositioned at the gap δ1, the other ones are surely on the treadssurfaces 112 a and 112 b. Accordingly, the swing and vertical vibrationsof the vehicle 2 are reduced by the degree described above. The detailedexplanation is as follows.

For example, as shown in FIG. 39, even when the front end idler 16Arides on the tread surfaces 112 a and 112 b and the rear end idler 16Bis positioned at the gap δ1, the final roller 14B rides on the treadsurfaces 112 a and 112 b. Accordingly, an angle of swing θA, which isgenerated as a result of the rear end idler 16B falling into the gap δ1,is decreased. In FIG. 39, the sprocket 12, receiving the weight of thevehicle 2, is placed at the almost center of the portion between thefront end idler 16A and the rear end idler 16B. Specifically, a verticalline, which passes through the sprocket 12, receiving the dead weight ofthe vehicle 2, passes the left side of the final roller 14B in FIG. 39(opposite side to the rear end idler 16B). Accordingly, even when therear end idler 16B is positioned at the gap δ1, the rear end idler 16Bcan be prevented from falling into the gap δ1. Specifically, verticalmovement of the sprocket 12 (specifically, of the vehicle 2) is reduced.

Though the explanation is made with the aforesaid crawler belt 11 beinga crawler belt made of rubber, the same effect as described above isobtained even with a crawler belt made of metal, if in the crawler belt11, the tread surfaces 112 a and 112 b for the front and the rear idlers16A and 16B, and the rollers 14A and 14B are placed at a predeterminedpitch with the gap δ1 between them. In the aforesaid explanation, thenumber of the rollers 14A and 14B is two, but as shown in FIG. 40, withthe roller 14 having three or more rollers 14A, . . . , 14Z, the sameeffect as described above can be obtained if the placement is the sameas described above. When the aforesaid placement is applied to the thirdembodiment, it is suitable if the rear end idler 16B is replaced for thesprocket 12, and in this case, the same effect as described above can bealso obtained.

Next, examples of the sprocket 12 and the crawler belt 11, preferablefor the first to the third embodiments, will be described with referenceto FIGS. 41-44. As shown in FIGS. 41 and 42, the crawler belt is made ofrubber, and has raised portions 115 in the center portion of the innersurface at predetermined pitches in order in the direction in which thecrawler belt 11 is passed around. Meanwhile, the sprocket 12 has aplurality of engaging gears 121 with the aforesaid raised portions 115on the outer perimeter thereof. The sprocket 12 has an external diameterD2 which is smaller than an external diameter D1 of the tops of theengaging gears 121 (D1>D2, (D1−D2)/2=δ2), and is fixedly provided withcylinder members 122 a and 122 b, which can be abutted to the surfacesurrounding the aforesaid raised portions 115 on the outer perimetersurface thereof, on the right and left sides of the engaging gears 121.Specifically, a doughnut-shaped disc 123 is clamped with a bolt 124 onthe outer perimeter of the sprocket 12, and round bars (hereinafter,referred to as round bars 121), which are engaging gears 121, arefixedly provided at the outer perimeter of the disc 123 at predeterminedpitches. The round bars 121 are fixedly provided at the outer perimeterof the disc 123 by means of right and left ribs 125 with thelongitudinal direction thereof being in a lateral direction of thevehicle 2. The cylinder members 122 a and 122 b are also fixed at thedisc 123 by the ribs 125. The crawler belt 11 and the sprocket 12 withthe aforesaid configuration have the following operational effects.

As shown in FIGS. 42 and 43, when the crawler belt 11 is engaged with around bar 121, the round bar 121 engages the bottom and side surfaces ofthe raised portion 115 of the crawler belt 11 by δ2. At the same time,the outer perimeter surfaces of the cylinder members 122 a and 122 b arebrought into forceful contact with the surface surrounding the raisedportion 115 of the crawler belt 11. Accordingly, the crawler belt 11obtains a rotational driving force from the sprocket 12. Here, thecrawler belt 11 does not need the core metals 112 in the crawler belt 11made of rubber, which is described in the explanation of the aforesaidembodiments, thereby reducing the weight. Accordingly, the sprocket 12can transmit a highly efficient rotational force to the crawler belt 11.Specifically, a higher tractive force is obtained, the separation of thecrawler 11 is difficult to occur by the amount of engagement δ, slip isdifficult to occur, and the weight, the noise, and the cost can bereduced. As is obvious from FIG. 44 showing contact relationshipbetween, for example, the roller 14A and the crawler belt 11, the raisedportion 115 is housed in a center recessed portion of the rollers 14Aand 14B, and the front and rear idlers 16A and 16B; therefore, thedisadvantage of the separation of the crawler belt 11 can be alsoeliminated, as seen from this aspect.

The sprocket 12 in the aforesaid first, second, and third embodimentshas a configuration all of the driving force is obtained from thevehicle 2, but, needless to say, a type in which the wheel hub 31contains, for example, a hydraulic motor or the like can be suitable.

INDUSTRIAL AVAILABILITY

The present invention is useful as a crawler device for a crawler typeof vehicle which lowers the vehicle height, decreases the vehicle width,has excellent maintainability, does not stumble at an obstacle even whencolliding with the obstacle during traveling, and which exhibitsexcellent operation stability in a working vehicle with simplestructure.

What is claimed is:
 1. A crawler device suitable for use on a crawlervehicle having a pair of crawler devices on at least one of a frontportion of said vehicle and a rear portion of said vehicle, said crawlerdevice comprising: a truck frame; a sprocket, being a driving wheel; atleast one idler, being a driven wheel and being disposed on said truckframe; a crawler belt passed around said sprocket and said at least oneidler as an endless loop; a front end link coupled to a forward portionof said truck frame by a pin located at a lower end portion of saidfront end link; said front end link being adapted to be coupled to abody side of the vehicle by a pin located at an upper end portion ofsaid front end link; and a rear end link coupled to a rearward portionof said truck frame by a pin located at a lower end portion of said rearend link, said rear end link being adapted to be coupled to said bodyside at a position behind said front end link by a pin located at anupper end portion of said rear end link, wherein a quadric linkstructure, which is formed by said body side, said truck frame, saidfront end link, and said rear end link, has a length on said truck framewhich is shorter than its length on said body side.
 2. A crawler devicein accordance with claim 1, wherein a point of intersection (P) of anaxis of said front end link and an axis of said rear end link is locatedinside said endless loop.
 3. A crawler device in accordance with claim1, wherein at least one of a swing stopping mechanism for stopping aswing of said truck frame at any position and a swing control mechanismfor controlling a maximum swing of said truck frame, is provided betweensaid body side and said truck frame.
 4. A crawler device in accordancewith claim 1, wherein said truck frame is disposed below said sprocketwheel, and wherein said at least one idler comprises a front end idler,disposed at a front portion of said truck frame, and a rear end idler,disposed at a rear portion of said truck frame.
 5. A crawler device inaccordance with claim 4, wherein a point of intersection (P) of an axisof said front end link and an axis of said rear end link is locatedinside said endless loop.
 6. A crawler device in accordance with claim4, further comprising: at least one roller positioned at a lower portionof said truck frame between said front end idler and said rear endidler; wherein said crawler belt has tread surfaces, in a protrusionform at a predetermined pitch spaced with a predetermined gap, to betrod by said front end idler, said rear end idler, and said at least oneroller; and wherein a distance between said front end idler and a rolleradjacent to said front end idler, a distance between said rear end idlerand a roller adjacent to said rear end idler, and a distance betweensaid front end idler and said rear end idler are each expressed by[(0.5±0.2)+N]×Lp where N is set as zero or a natural number, and Lp isset as a crawler belt pitch.
 7. A crawler device in accordance withclaim 4, wherein at least one of a swing stopping mechanism for stoppinga swing of said truck frame at any position and a swing controlmechanism for controlling a maximum swing of said truck frame, isprovided between said body side and said truck frame.
 8. A crawlervehicle having a pair of crawler devices on at least one of a frontportion of said vehicle and a rear portion of said vehicle, each saidcrawler device comprising: a truck frame; a sprocket, being a drivingwheel; at least one idler, being a driven wheel and being disposed saidtruck frame; a crawler belt passed around said sprocket and said atleast one idler as an endless loop; a front end link being coupled to aforward portion of said truck frame by a pin located at a lower endportion of said front end link; said front end link being coupled to abody side of the vehicle by a pin located at an upper end portion ofsaid front end link; and a rear end link being coupled to a rearwardportion of said truck frame by a pin located at a lower end portion ofsaid rear end link; said rear end link being coupled to said body sideat a position behind said front end link by a pin located at an upperend portion of said rear end link, wherein in each crawler device aquadric link structure, which is formed by said body side, said truckframe, said front end link, and said rear end link, has a length on saidtruck frame which is shorter than its length on said body side.
 9. Acrawler vehicle in accordance with claim 8, wherein in each crawlerdevice a point of intersection (P) of an axis of said front end link andan axis of said rear end link is located inside said endless loop.
 10. Acrawler vehicle in accordance with claim 8, wherein each crawler devicefurther comprises: at least one roller positioned at a lower portion ofsaid truck frame between said front end idler and said rear end idler;wherein said crawler belt has tread surfaces, in a protrusion form at apredetermined pitch spaced with a predetermined gap, to be trod by saidfront end idler, said rear end idler, and said at least one roller; andwherein a distance between said front end idler and a roller adjacent tosaid front end idler, a distance between said rear end idler and aroller adjacent to said rear end idler, and a distance between saidfront end idler and said rear end idler are each expressed by[(0.5±0.2)+N]×Lp where N is set as zero or a natural number, and Lp isset as a crawler belt pitch.
 11. A crawler vehicle in accordance withclaim 8, wherein in each crawler device at least one of a swing stoppingmechanism for stopping a swing of said truck frame at any position and aswing control mechanism for controlling a maximum swing of said truckframe, is provided between said body side and said truck frame.
 12. Acrawler vehicle in accordance with claim 8, wherein in each crawlerdevice said truck frame is disposed below said sprocket wheel, andwherein said at least one idler comprises a front end idler, disposed ata front portion of said truck frame, and a rear end idler, disposed at arear portion of said truck frame.
 13. A crawler vehicle in accordancewith claim 12, wherein in each crawler device a point of intersection(P) of an axis of said front end link and an axis of said rear end linkis located inside said endless loop.
 14. A crawler vehicle in accordancewith claim 12, wherein each crawler device further comprises: at leastone roller positioned at a lower portion of said truck frame betweensaid front end idler and said rear end idler; wherein said crawler belthas tread surfaces, in a protrusion form at a predetermined pitch spacedwith a predetermined gap, to be trod by said front end idler, said rearend idler, and said at least one roller; and wherein a distance betweensaid front end idler and a roller adjacent to said front end idler, adistance between said rear end idler and a roller adjacent to said rearend idler, and a distance between said front end idler and said rear endidler are each expressed by [(0.5±0.2)+N]×Lp where N is set as zero or anatural number, and Lp is set as a crawler belt pitch.
 15. A crawlervehicle in accordance with claim 12, wherein each crawler device furthercomprises at least one of a swing stopping mechanism for stopping aswing of said truck frame at any position and a swing control mechanismfor controlling a maximum swing of said truck frame, provided betweensaid body side and said truck frame.